U.S. patent number 6,205,385 [Application Number 09/413,269] was granted by the patent office on 2001-03-20 for power takeoff control switches.
This patent grant is currently assigned to Case Corporation. Invention is credited to William A. Itzenhuiser, William L. Schubert, Michael Stelzle.
United States Patent |
6,205,385 |
Stelzle , et al. |
March 20, 2001 |
Power takeoff control switches
Abstract
A control system is disclosed for controlling a power takeoff
(PTO) shaft of a work vehicle (e.g., a tractor). The work vehicle
includes an engine and an operator station, and the PTO shaft
transfers power from the engine to an implement. The control system
includes a remote switch, a vehicle speed sensor, and a control
circuit. The remote switch is located remotely from the operator
station and provides a remote switch signal to the control circuit
to engage and disengage rotational movement of the PTO shaft. The
vehicle speed sensor provides a vehicle speed signal to the control
circuit representative of a speed of the work vehicle. The control
circuit receives the remote switch signal and the vehicle speed
signal and, when the vehicle speed signal exceeds a predetermined
vehicle speed, the control circuit prevents engagement and
disengagement of the PTO shaft with the remote switch.
Inventors: |
Stelzle; Michael (Aurora,
IL), Schubert; William L. (Downers Grove, IL),
Itzenhuiser; William A. (Naperville, IL) |
Assignee: |
Case Corporation (Racine,
WI)
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Family
ID: |
23135289 |
Appl.
No.: |
09/413,269 |
Filed: |
October 6, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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294868 |
Apr 20, 1999 |
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Current U.S.
Class: |
701/50; 172/2;
172/3; 180/53.6; 180/53.7; 477/111; 701/69 |
Current CPC
Class: |
A01B
63/1117 (20130101); A01B 71/06 (20130101); B60K
25/00 (20130101); Y10T 477/68 (20150115); Y10T
477/675 (20150115) |
Current International
Class: |
A01B
63/111 (20060101); A01B 71/00 (20060101); A01B
71/06 (20060101); B60K 25/00 (20060101); G06F
007/70 (); G06F 019/00 () |
Field of
Search: |
;701/50,69
;74/15.86,15.8,15.63,11 ;180/53.6,53.62,53.61,53.7 ;477/111,107
;172/2,3 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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002935 U1 |
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Jan 1999 |
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AT |
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2605681A1 |
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Aug 1977 |
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DE |
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3706115A1 |
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Sep 1987 |
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DE |
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4204803A1 |
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Aug 1993 |
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DE |
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4428368C2 |
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Feb 1996 |
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DE |
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19630419A1 |
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Jan 1998 |
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DE |
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448281A1 |
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Mar 1991 |
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EP |
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443325A1 |
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Aug 1991 |
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EP |
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517384B1 |
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Apr 1996 |
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EP |
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920793A2 |
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Jun 1999 |
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EP |
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Other References
Lelyterra 35/45-series, printed Apr. 19, 1999 from
http://www.lely.com/default.asp?page= . . .
untry=12&produktTypeID=1&ArtikellD=26; p. 1 of 1. .
Brochure entitled Case IH 1260 & 1360 Ginder Mixers,
.COPYRGT.1997; 4 pages (entire brochure). .
Brochure entitled Case IH 3200/4200 Series Tractors, .COPYRGT.1994;
29 pages (entire brochure)..
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Primary Examiner: Cuchlinski, Jr.; William A.
Assistant Examiner: Hernandez; Olga
Attorney, Agent or Firm: Foley & Lardner
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation application of U.S. Pat. Appl.
No. 09/294,868, entitled "Power Takeoff Control System", filed on
Apr. 20, 1999 by Stelzle et al.
Claims
What is claimed is:
1. A method of controlling a power takeoff shaft of a work vehicle,
the work vehicle having an operator station, the method
comprising:
receiving an ON signal from a remote switch located remotely from
the operator station;
engaging the power takeoff shaft when the ON signal is
received;
receiving an OFF signal from a local switch mounted within the
operator station, the OFF signal being sent when the local switch
is moved from a first OFF position to a second OFF position;
and
disengaging the power takeoff shaft when the OFF signal is
received.
2. The method of claim 1, wherein the second OFF position is a
momentary position.
3. The method of claim 1, further comprising, after the step of
disengaging, engaging the power takeoff shaft when a second ON
signal is received from the remote switch.
4. A system for controlling the power takeoff shaft of a work
vehicle, the work vehicle having an operator station,
comprising:
means for receiving an ON signal from a remote switch located
remotely from the operator station;
means for engaging the power takeoff shaft when the ON signal is
received;
means for receiving an OFF signal from a local switch mounted
within the operator station, the OFF signal being sent when the
local switch is moved from a first OFF position to a second OFF
position; and
means for disengaging the powexgatoff shaft when the OFF signal is
received.
5. The system of claim 4, wherein the second OFF position is a
momentary position.
6. The system of claim 4, further comprising means for re-engaging
the power takeoff shaft after the power takeoff shaft is disengaged
by the means for disengaging when a second ON signal is
received.
7. The system of claim 4, further comprising means for receiving an
ON signal from the local switch.
8. A control system for controlling a power takeoff shaft of a work
vehicle, the work vehicle having an operator station, the control
system comprising:
a local switch mounted within the operator station and having a
first OFF position and a second OFF position;
a remote switch located remotely from the operator station and
having an ON position; and
a control circuit coupled to the local switch and the remote
switch, the control circuit configured to engage the power takeoff
shaft when the remote switch is moved to the ON position and to
disengage the power takeoff shaft when the local switch is moved
from the first OFF position to the second OFF position.
9. The control system of claim 8, wherein the first OFF position is
a maintained position.
10. The control system of claim 8, wherein the remote switch also
has an OFF position, the control circuit configured to engage the
power takeoff shaft when the local switch is in the first OFF
position and the remote switch is moved from the OFF position to
the ON position.
11. The control system of claim 8, wherein the second OFF position
is a momentary position.
12. The control system of claim 8, wherein the local switch also
has an ON position.
13. The control system of claim 12, wherein the local switch
requires secondary motion to move from the first OFF position to
the ON position.
14. The control system of claim 12, wherein the remote switch also
has an OFF position, the control circuit configured to disengage
the power takeoff shaft when the local switch is in the ON position
and the remote switch is moved to the OFF position.
15. A control system for controlling a power takeoff shaft of a
work vehicle, the work vehicle having an operator station, the
control system comprising:
first switch means mounted within the operator station and having a
first OFF position and a second OFF position;
second switch means located remotely from the operator station and
having an ON position; and
control means for engaging the power takeoff shaft when the second
switch means is moved to the ON position and for disengaging the
power takeoff shaft when the first switch means is moved from the
first OFF position to the second OFF position.
16. The control system of claim 15, wherein the second OFF position
is a momentary position.
17. The control system of claim 15, wherein the second switch means
includes an ON pushbutton and an OFF pushbutton.
18. The control system of claim 15, wherein the first OFF position
is a maintained position.
19. The control system of claim 15, wherein the second switch means
also has an OFF position, the control means engaging the power
takeoff shaft when the first switch means is in the first OFF
position and the second switch means is moved from the OFF position
to the ON position.
20. The control system of claim 15, wherein the first switch means
also has an ON position.
21. The control system of claim 20, wherein the first switch means
requires secondary motion to move from the first OFF position to
the ON position.
22. The control system of claim 48, wherein the second switch means
also has an OFF position, the control means disengaging the power
takeoff shaft when the first switch means is in the ON position and
the second switch means is moved to the OFF position.
Description
FIELD OF THE INVENTION
The present invention relates generally to control systems for
engagement and disengagement of a power takeoff. More specifically,
the present invention relates to control systems for engagement and
disengagement of a power takeoff shaft of a work vehicle such as a
tractor.
BACKGROUND OF THE INVENTION
Many work vehicles (e.g., agricultural vehicles such as tractors;
construction vehicles such as skid-steers) in use today include at
least one power takeoff (PTO) shaft. A PTO shaft allows the farmer
to operate implements and other farm machinery using power provided
by the tractor engine. Common PTO-driven implements include balers,
mowers, grinder mixers, augers, drills, etc. Some of these
implements are driven while the tractor travels across a field
(e.g., balers and mowers) while others are driven while the tractor
is stationary (e.g., augers, drills, blowers, feeders, grinders and
manure pumps). Still others may be driven while the tractor is
either stationary or traveling (e.g., grinder mixers).
Ease of operator use and flexibility of controls are important
considerations when designing an operator control system for PTOs.
In some prior systems, a control switch has been provided in the
operator station (e.g., cab or platform) of the work vehicle to
allow the operator to engage and disengage the PTO shaft to the
engine of the work vehicle. These operator station-mounted switches
are useful for applications where the tractor is in motion since
the operator is typically in the operator station while farming.
However, when an auger or drill is driven by the PTO shaft, the
operator must continuously walk back to the operator station to
turn the PTO shaft on and off using the operator station-mounted
switch.
Accordingly, remote switches have been mounted at various locations
around the work vehicle (e.g., on the front or rear fender of the
vehicle) to allow the operator to control the PTO from outside the
operator station of the work vehicle. Various control systems have
been introduced to determine when the remote switch is active and
when the operator station-mounted switch is active. For example, in
one prior system, a selector switch is provided in the operator
station to select between a standard mode (operator station-mounted
switch active) and a remote mode (fender-mounted switch active).
One drawback of this control system occurs when the operator wishes
to switch from remote mode back to standard mode. The operator must
actively switch the system from the remote mode to the standard
mode when the operator enters the vehicle and begins farming the
field with a PTO-driven implement. If the operator forgets to
actuate this selector switch, the remote switch is still active.
Thus, a stray twig, stalk or other obstruction may actuate the
remote switch, turning the remote PTO on or off unbeknownst to the
operator, causing operator confusion. The operator may also travel
some distance before realizing this error, requiring the operator
to re-farm the missed portion of the field, wasting valuable time
and resources.
Farm equipment manufacturers are beginning to realize the
advantages of automating certain controls on the work vehicle. For
example, when the work vehicle reaches the end of a row in the
field (i.e., the headland), the operator must perform several tasks
at once, including such things as turning the PTO shaft off,
raising the hitch which is coupled to the implement, disabling
mechanical front-wheel drive (MFD), disabling differential lock
(DL), etc. Then, as the tractor re-enters the field after turning
around on the headland, the operator must perform the opposite of
these same tasks. Thus, attempts have been made in the prior art to
automate one or more of these tasks performed when the work vehicle
reaches the headland. Additional functionality and flexibility is
demanded by operators to allow them to customize this automation
procedure for various farming processes.
Accordingly, what is needed is an improved control system for a PTO
having remote switches which improves the ease of use of the remote
switches without significantly affecting operability or
functionality. Also what is needed is a system to add new
functionality and flexibility to the automation of PTO control when
the work vehicle reaches and turns around on the headland.
SUMMARY OF THE INVENTION
These and other limitations of the prior art are overcome by the
present invention which, according to an exemplary embodiment,
includes a control system for controlling a power takeoff shaft of
a work vehicle having an operator station. The control system
includes a remote switch, a vehicle speed sensor and a control
circuit. The remote switch is located remotely from the operator
station and provides a remote switch signal to control the power
takeoff shaft. The vehicle speed sensor provides a vehicle speed
signal representative of a speed of the work vehicle. The control
circuit, coupled to the remote switch and the vehicle speed sensor,
receives the remote switch signal and the vehicle speed signal.
When the speed of the work vehicle exceeds a predetermined speed,
the control circuit prevents control of the power takeoff shaft
with the remote switch signal.
According to another exemplary embodiment of the present invention,
a control system for controlling a power takeoff shaft of a work
vehicle having an operator station is provided. The control system
includes remote switch means for providing a remote switch signal
to control the power takeoff shaft, and a vehicle speed sensor
means for providing a vehicle speed signal representative of a
speed of the work vehicle. The control system further includes
control means coupled to the remote switch means and the vehicle
speed sensor means for receiving the remote switch signal and the
vehicle speed signal and, when the speed of the work vehicle
exceeds a predetermined vehicle speed, for preventing control of
the power takeoff shaft with the remote switch signal.
According to another exemplary embodiment of the present invention,
a method for controlling a power takeoff shaft of a work vehicle is
provided. The method includes providing a remote switch signal to
control the power takeoff shaft, providing a vehicle speed signal
representative of a speed of the work vehicle, and preventing
control of the power takeoff shaft with the remote switch signal
when the speed of the work vehicle exceeds a predetermined vehicle
speed.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will become more fully understood from the following
detailed description, taken in conjunction with the accompanying
drawings, wherein like reference numerals refer to like parts, and
in which:
FIGS. 1A-1B are diagrams of a tractor having a PTO shaft capable of
driving implements while traveling (FIG. 1A) and while stationary
(FIG. 1B) according to an exemplary embodiment of the present
invention;
FIG. 2 is a block diagram of the control system for the tractor and
implement of FIGS. 1A and 1B according to an exemplary embodiment
of the present invention;
FIG. 3 is a flow chart showing the control flow of the control
system of FIG. 2 according to one feature of the present
invention;
FIG. 4 is a diagram of an alternative embodiment of the exemplary
operator interface unit shown in FIG. 1A; and
FIG. 5 is a diagram of another alternative embodiment of the
exemplary operator interface unit shown in FIG. 1A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1A, a work vehicle 10 is shown pulling an
implement 12. Work vehicle 10 may be any type of agricultural or
construction vehicle, such as, a Case Model 4240 tractor. Implement
12 may be any type of implement, such as, a rotary harrow, for
example, a Lelyterra 35/45-series rotary harrow. Vehicle 10
includes an operator station 14, a hitch 16 and a power takeoff
(PTO) shaft 18. Vehicle 10 further includes a control unit 64
coupled to a pair of remote PTO control switches 22, 24, a remote
hitch control switch 23, a vehicle speed sensor 25, a hitch
position sensor 27 and an operator interface unit 20. The
positioning of switches 22, 23 and 24 is selected to allow a direct
view of a drive shaft 26 of implement 12 by an operator standing
behind vehicle 10 using switches 22, 23 and 24. In one embodiment,
remote PTO switches 22 and 24 are located outboard of rear brake
lights 31, 33 on left and right fenders 35. Remote hitch control
switch 23 is located inboard of rear brake light 31. A second
remote hitch control switch can be similarly located inboard of
brake light 33. Operator interface unit 20 includes PTO control
switches 2 and hitch control switches 4. PTO control switches 2
include an operator station-mounted PTO ON/OFF control switch 1, a
PTO remote/local selector switch 3 and an auto PTO mode switch 5.
Hitch control switches 4 include a hitch position command switch 9
and a hitch UP/DOWN switch 11.
Implement 12 is coupled to vehicle 10 at hitch 16 and further
includes a drive shaft 26 and a driven member 28. Hitch 16 may be,
for example, a three-position hitch such as that shown in commonly
assigned U.S. Pat. No. 5,421,416 to Orbach et al. entitled "Hitch
Assembly Control System" or commonly assigned U.S. Pat. No.
5,601,146 to Schlegel et al. entitled "Hitch Assembly for a
Tractor," both patents hereby incorporated by reference. In this
embodiment, driven member 28 is a blade for a mower. PTO shaft 18
is engaged to the engine (not shown) of vehicle 10 in response to
control signals from control circuit 64. In response, PTO shaft 18
begins rotating at, for example, 540 or 1000 rotations per minute,
driving at 40 to 150 horsepower or more. Since PTO shaft 18 is
coupled to drive shaft 26 which is itself coupled to driven member
28, as vehicle 10 traverses an agricultural field, the engine of
vehicle 10 provides the necessary power to drive the driven member
28 to thereby work a field. According to one advantageous feature
of the present invention, while vehicle 10 is travelling, remote
PTO control switches 22, 24 are disabled to prevent inadvertent
actuations as described hereinafter.
Referring now to FIG. 1B, vehicle 10 is shown coupled to a second
implement 30. Second implement 30 is, for example, a Case Model
1260 grinder-mixer. Implement 30, like implement 12, includes a
drive shaft 32 and one or more driven members 34, 36 (e.g., a
hammermill, an auger feeder, etc). Again, since PTO shaft 18 is
coupled to drive shaft 32 which is itself selectively coupled to
one or more of driven members 34, 36, the engine of vehicle 10
provides the necessary power to drive driven members 34, 36 for
loading, grinding, mixing, and unloading feed or other product. In
this embodiment, vehicle 10 is stationary while driven members 34,
36 of implement 30 are driven. Accordingly, an operator 38 standing
outside vehicle 10 uses remote PTO switches 22, 24 (see FIG. 1A)
for convenience to engage and disengage PTO shaft 18.
Referring to FIG. 2, a PTO control system 50 for vehicle 10 is
shown. One example of a PTO control system is disclosed in commonly
assigned application Ser. No. 09/262,713, filed Mar. 4, 1999,
entitled "Power Take Off Engagement Control System", which is
hereby incorporated by reference. An engine 52 provides power to
the drive wheels (not shown) of vehicle 10 and, in addition,
provides power to apply rotational motion to a multi-plate,
hydraulically-actuated PTO clutch 54. An output shaft 56 of clutch
54 is shown directly coupled to a 1000 RPM PTO (high speed PTO)
shaft 18 and optionally coupled to a 540 RPM PTO (low speed PTO)
shaft 60 by a reduction gear 62. In the embodiment shown, PTO shaft
18 is used to drive the implement. In alternative embodiments, PTO
shaft 60 could drive the implement, or other PTO speeds may be
used.
Control system 50 includes a control circuit 64 (e.g., including
one or more digital microprocessors such as an Intel TN83C51FA
microprocessor or other digital or analog circuitry, a memory,
inputs/outputs, etc.) coupled to operator station-mounted PTO
ON/OFF control switch 1, PTO remote/local selector switch 3, auto
PTO mode switch 5, hitch position command switch 9, hitch UP/DOWN
switch 11, remote PTO control switches 22, 24, remote hitch control
switch 23, vehicle speed sensor 25, hitch position sensor 27 and a
hydraulic clutch control valve 68. Vehicle speed sensor 25 includes
a ground speed radar, but may alternatively include a transmission
output speed sensor which counts the teeth in a ring gear of the
transmission of vehicle 10 to determine if the vehicle is moving.
Vehicle speed sensor 25 may alternatively include a wheel speed
sensor or other system for providing a signal indicative of the
speed of vehicle 10. Hydraulic clutch control valve 68 is
controlled by control circuit 64 to selectively engage and
disengage PTO clutch 54 via a hydraulic conduit 69. When PTO clutch
54 is engaged, power from engine 52 is transmitted to output shaft
56. Control system 50 may further include a hydraulically-actuated
or spring-actuated brake 70 to inhibit rotational motion of output
shaft 56 when PTO clutch 54 is disengaged. Control system 50
includes a hydraulic valve 72 connected to brake 70 by a hydraulic
conduit 74 to engage and disengage brake 70. Control circuit 64
provides control signals to valves 68, 72 (e.g., analog or digital
signals, pulse-width modulated (PWM) signals, amplitude-modulated
or frequency-modulated signals, or other control signals.)
Also shown in FIG. 2 is an implement 12, 30 that may be coupled to
vehicle 10. Implement 12, 30 includes driven members 75 (e.g.,
driven member 28, driven members 34, 36) which are operated using
power from engine 52 when clutch 54 is engaged. Implement 12, 30
receives power from engine 52 via drive shaft 26, 32 coupled, in
this embodiment, to high speed PTO shaft 18 via a coupler 76. When
PTO clutch 54 is engaged and is transmitting power from engine 52
to output shaft 56 and high speed PTO shaft 18, power is
transmitted to implement drive shaft 26, 32 and to driven members
75 to perform one or more of a plurality of implement
functions.
Remote PTO
According to one feature of the present invention, control circuit
64 receives remote control signals from remote PTO control switches
22, 24, a local PTO control signal from operator station-mounted
PTO control switch 1, and a vehicle speed signal from vehicle speed
sensor 25. In the exemplary embodiment, remote PTO switches 22, 24
each include a pair of momentary pushbuttons and are mounted on
opposite sides of vehicle 10 and, preferably, on opposite sides of
PTO shaft 18 (or low speed PTO shaft 60). Thus, the operator does
not have to climb or reach over implement drive shaft 26, 32 when
the implement is coupled to PTO shaft 18 to reach the remote
control pushbuttons. Advantageously, remote PTO control switches
22, 24 are located such that operator 38 standing on the ground
outside of operator station 14 has a direct view of implement drive
shaft 26, 32 from either remote switch location. When vehicle speed
sensor 25 indicates that vehicle 10 is travelling at or above a
predetermined vehicle speed, e.g., one mile per hour (MPH), control
circuit 64 prevents engagement or disengagement of PTO clutch 54
based on the remote switch signal, effectively disabling remote PTO
control switches 22, 24. This feature prevents inadvertent enabling
and disabling of PTO clutch 54 via remote PTO control switches 22,
24 when vehicle 10 is in motion, such as, via a twig, stalk, or
worker running alongside vehicle 10. Preferably, operator
station-mounted PTO control switch 1 is still enabled when vehicle
10 is travelling to allow the operator within operator station 14
to engage and disengage the PTO shaft from operator station 14.
A flow diagram of a control flow according to an exemplary
embodiment of this feature is disclosed in FIG. 3. The routine
starts at step 100. At step 102, control circuit 64 determines if a
signal is being received from operator station-mounted PTO control
switch 1. If so, at step 104, control circuit 64 controls
engagement or disengagement of the PTO based on the signal received
from operator station-mounted switch 1. Subsequently, the routine
ends at step 106. If not, the control flow proceeds to step 108, to
obtain a vehicle speed signal from vehicle speed sensor 25 and
scale it to engineering units (e.g., miles per hour, kilometers per
hour, etc.). After step 108, the flow proceeds to step 110 to test
if the vehicle speed is greater than the predetermined vehicle
speed. As discussed hereinbefore, this predetermined vehicle speed
may be one MPH, less than one MPH, or more than one MPH (e.g., 10
MPH) and may be programmable by a service technician or preset
during manufacturing. If the measured speed is greater than the
predetermined vehicle speed, the control flow ends at step 106
without checking the remote PTO switches 22, 24, effectively
disabling or disallowing control of the PTO based upon the remote
switch signal. Alternatively, the remote switch or switches are
checked at step 112. If a remote switch is pressed, the PTO shaft
is engaged or disengaged based on the remote switch position or
signal at step 114. The routine may begin again at step 100 and
runs intermittently, selectively, or periodically throughout
operation of the PTO.
Referring now to FIG. 4, an exemplary embodiment of operator
interface unit 20 is shown with operator-adjustable switches in
various exemplary configurations. Various PTO control and hitch
control switch configurations may be employed to facilitate
operator control of the PTO shaft and hitch position. Switches 1,
3, 5, 9, 11, 22, 23 and 24 may include any type of switch, such as,
digital switches, analog switches, buttons, portions of a graphical
user interface, etc., and may provide any type of control signal,
such as, digital or analog signals. In this exemplary embodiment,
however, switches 1 and 3 are maintained, two-position switches.
Switch 1 allows the operator, while at the operator station, to
manually engage or disengage the PTO shaft. Switch 3 allows the
operator to select between remote PTO switch control (i.e., via
remote PTO control switches 22, 24) and operator station-mounted
PTO switch control (i.e., via switch 1). Switch 5 is a
three-position rocker switch having an AUTO PTO OFF position
(maintained), an AUTO PTO ON position (maintained) and a SET
position (momentary), the function of which will be described
hereinafter. Switch 9 is a slidable switch to allow the operator to
set the position of the hitch relative to a maximum position and a
minimum position. For example, when switch 9 is slid to a new
position, control circuit 64 sends command signals to raise or
lower the hitch at a predetermined speed until the selected hitch
position is attained. Switch 11 is a three-position momentary
switch having an UP position (maintained), a first DOWN position
(maintained) and a second DOWN position (momentary). Switch 11
commands control circuit 64 to raise the hitch as long as the
switch is in the UP position or until the hitch reaches the maximum
hitch height position, to lower the hitch as long as the switch is
in first DOWN position or until the hitch reaches the minimum hitch
height position, and to drop the hitch, allowing gravity to pull
the hitch to its lower-most position, when the operator actuates
the second DOWN position twice in rapid succession.
In the embodiment of FIG. 4, the operator uses switch 3 to select
between remote PTO switch control and operator station-mounted PTO
switch control. Alternatively, switch 3 may be absent from control
interface 20 and the operator may use either or both remote PTO
control switches 22, 24 and operator station-mounted switch 1 at
any time to control engagement and disengagement of PTO shaft 18.
In the former embodiment, the operator cannot operate the PTO from
the remote switches without first entering the operator station to
adjust switch 3 to its REMOTE position, an inconvenience to the
operator. In the latter embodiment, if operator station-mounted
switch 1 is turned ON and one of remote switches 22, 24 is used to
turn the PITO OFF, operator confusion may result when the operator
returns to the operator station and wishes to turn the PTO ON when
switch 1 is already in the ON position.
Accordingly, referring now to FIG. 5, one advantageous modification
includes the replacement of switch 1 and two-position switch 3 with
a single three-position switch 200 having a PTO OFF position
(maintained) 202, a PTO ON position (maintained) 204 and an OFF
CHANGE OF STATE position (momentary) 206. In operation, with the
vehicle being stationary, when three-position switch 200 is in PTO
OFF position 204, actuation of one of remote switches 22, 24 to the
ON position will override the PTO OFF signal from three-position
switch 200 and the controller will engage the PTO. Actuating one of
remote switches 22, 24 to the OFF position will turn the PTO shaft
off again. To turn off the PTO shaft from inside the operator
station after having turned it on remotely, the operator moves the
three-position switch 200 to OFF CHANGE OF STATE position 204
momentarily, then releases it to disengage the PTO shaft. Thus,
this feature allows the operator to turn off the PTO shaft from
inside the operator station after it has been turned on with remote
switches 22, 24 without operator confusion.
According to one embodiment, the three-position switch 200 has a
structure requiring secondary motion in order to actuate the switch
to PTO ON position 202. For example, three-position switch 200 may
have a button that must be pressed before the switch can be pulled
upward into PTO ON position 202.
Remote PTO control switches 22, 24 each include, according to one
exemplary embodiment, a first ON pushbutton and a second OFF
pushbutton. In order to turn the PTO on from remote switches 22,
24, control circuit 64 requires the first ON pushbutton be pressed
and held for a predetermined time (e.g., about 3 seconds) before
the PTO shaft will be engaged. In order to turn the PTO off from
remote switches 22, 24, control circuit 64 immediately turns the
PTO off when the second OFF pushbutton is pressed. Furthermore, the
surface of the second OFF pushbutton is raised a slight distance
(e.g., 3-4 millimeters) higher than the first ON pushbutton.
For PTO control from the operator station, the operator actuates
the three-position switch 200 to ON position 202 which engages the
PTO shaft. As a further feature, three-position switch 200 can
require two-motion actuation (i.e., lift and move) to prevent
inadvertent engagement of the PTO shaft. The PTO shaft may then be
disengaged by movement of three-position switch 200 to OFF 204 or
OFF CHANGE OF STATE 206. With three-position switch 200 in ON
position 202, the remote switches may still be used to engage and
disengage the PTO shaft. Thus, this feature allows the operator to
turn off the PTO shaft remotely after it has been turned on from
the operator station.
As a further feature, a PTO indicia 40 (e.g., a light emitting
diode or other light or sound) is present on control interface 20.
PTO indicia 40 is steadily lit when the PTO is engaged from the
operator station-mounted three-position switch 200 and is turned
off when the PTO is disengaged from three-position switch 200. When
the PTO is turned on via three-position switch 200 and subsequently
turned off via remote switches 22, 24, PITO indicia 40 will flash,
since three-position switch 200 is still in ON position 202. To
turn PTO indicia 40 off, three-position switch 200 must be moved to
OFF position 204.
According to yet another feature, control circuit 64 will disable
the PTO completely if a remote PTO OFF signal is received from
remote PTO control switches 22, 24 for more than a predetermined
amount of time (e.g., 30 seconds), after which PTO indicia 40 will
flash indicating a PTO control system error. However, if a remote
PTO ON signal is received from remote PTO control switches 22, 24
for the predetermined amount of time, control circuit 64 will wait
until the operator turns the PTO off either via an operator
station-mounted switch 1 or via remote switches 22, 24, after which
control circuit 64 will disable PTO control via remote switches 22,
24.
Auto PTO
According to another advantageous feature of the present invention,
engagement and disengagement of the PTO shaft is performed
automatically by control circuit 64 when the work vehicle reaches
the headland at the end of a row or re-enters the row after turning
on the headland. Automatic control of the PTO shaft is based on the
hitch position, as received from hitch position sensor 27, and the
status of one or more operator-adjustable hitch position switches,
such as, auto PTO mode switch 5. According to one exemplary
embodiment, control circuit 64 includes a PTO controller to control
engagement and disengagement of the PTO shaft and a hitch
controller to control movement of the hitch and to sense the
position of the hitch. The hitch controller provides data to the
PTO controller via a data bus (e.g., RS485 or SAE J-1939 Controller
Area Network (CAN) bus), the data including the hitch position from
hitch position sensor 27, the setting of hitch position command
switch 9, the setting of hitch UP/DOWN switch 11, the setting of
remote hitch control switch 23 and a "hitch at upper limit" status
signal when the hitch has reached its maximum position. The PTO
controller also receives data from operator station-mounted PTO
ON/OFF control switch 1, PTO remote/local selector switch 3 and
auto PTO mode switch 5.
The operator begins AUTO PTO mode by first initializing a PTO OFF
set point and a PTO ON set point. The PTO ON set point is a hitch
position below which the PTO will automatically engage when in AUTO
PTO mode. The PTO OFF set point is a hitch position above which the
PTO will automatically disengage when in AUTO PTO mode. To
initialize set points, the operator moves the hitch to the desired
set point and actuates auto PTO mode switch 5 to its SET position
(momentary). One actuation sets the PTO OFF set point and two
actuations sets the PTO ON set point. The set points may be
initialized either with the PTO shaft rotating or with the PTO
shaft stationary, the former being preferred since it will allow
the operator to first identify "rattling" of the PTO shaft based on
the hitch position and consequently set the set points to minimize
this rattling when the hitch is raised and lowered at the
headlands.
Next, the operator selects AUTO PTO ON (maintained) using AUTO PTO
mode switch 5, PTO ON using operator station-mounted PTO ON/OFF
control switch 1, and then begins traversing the field. As the
operator approaches the headland, the operator raises the hitch
using either hitch position command switch 9 or hitch UP/DOWN
switch 11. The PTO is automatically disengaged when the hitch is
raised above the PTO OFF set point. As the operator drives out of
the headland, the operator lowers the hitch, again using either
hitch position command switch 9 or hitch UP/DOWN switch 11. The PTO
is automatically engaged when the hitch is lowered below the PTO ON
set point. An AUTO PTO indicia 42 (e.g., light emitting diode,
buzzer, etc.) is provided on operator interface 20 to indicate when
AUTO PTO mode is active. Since the PTO shaft typically takes
approximately 1.5 to 2.75 seconds to engage, including two set
points instead of one allows the operator to set the PTO ON set
point at a higher implement position than the PTO OFF set point to
allow the PTO shaft to be rotating at full speed before the
implement is completely lowered to the ground. Other advantages and
features of this flexible two set point system will be
apparent.
The system includes further features relating to the various
permutations of inputs from auto PTO mode switch 5, operator
station-mounted PTO switch 1, hitch position sensor 27, etc. For
example, if operator station-mounted PTO switch 1 is moved to its
OFF position while auto PTO mode switch 5 is still in its AUTO PTO
ON position, the PTO will be disengaged regardless of hitch
position since it is presumed this is what the operator intended.
As another example of such a feature, when the hitch is above the
PTO OFF set point, operator station-mounted PTO switch 1 is in the
ON position, and auto PTO mode switch 5 is moved from its AUTO PTO
ON position to its AUTO PTO OFF position, PTO indicia 40 will flash
and the PTO shaft will be disabled until operator station-mounted
PTO switch 1 is cycled from its ON to its OFF position and back to
its ON position.
The AUTO PTO mode described herein is a feature that adds
significant functionality to the PTO control system of FIG. 2.
However, the AUTO PTO function is only needed when the work vehicle
is traveling (e.g., the application shown in FIG. 1A), not when the
work vehicle is stationary (e.g., the application shown in FIG.
1B). Thus, according to another feature of the PTO control system,
control circuit 64 receives a vehicle speed signal from vehicle
speed sensor 25 and, when the speed is below a predetermined
vehicle speed (e.g., one mile per hour or less), control circuit 64
disables the AUTO PTO function. This feature prevents inadvertent
engaging and disengaging of the PTO based on the hitch position
when vehicle 10 is stationary. While this feature has particular
applicability when automatic engagement and disengagement of the
PTO is based on hitch position, it may also find applicability when
said automatic engagement and disengagement of the PTO is based on
other inputs, such as, an "end of row" command received from an
operator-adjustable switch or from control circuit 64 in which a
plurality of end-of-row functions (e.g., control of mechanical
front-wheel drive, differential lock, etc.) occurs in response to a
single command.
According to one embodiment of this feature, if the operator
actuates auto PTO mode switch 5 to the AUTO PTO ON position when
the speed is below the predetermined vehicle speed, the AUTO PTO
function will not be enabled and auto PTO indicia 42 will flash to
indicate to the operator that the AUTO PTO function cannot be
enabled. According to another embodiment of this feature, when in
AUTO PTO mode, if the hitch is above the AUTO PTO OFF set point and
the work vehicle 10 does not move for a predetermined period of
time (e.g., 10 seconds), the AUTO PTO mode is automatically
disabled and auto PTO indicia 42 flashes. Other embodiments of
disabling AUTO PTO based on a vehicle speed signal are
contemplated. The value of the predetermined vehicle speed may be
adjustable by a service technician or programmed during
manufacturing. The value is preferably sufficiently low to indicate
the absence of vehicle motion in spite of the standard tolerances
of vehicle speed sensor 25.
Several other features of the present control system also relate to
disabling the AUTO PTO mode. According to one feature, when either
of the remote PTO switches 22, 24 is actuated, AUTO PTO is
disabled. According to another feature, if the hitch is above the
AUTO PTO OFF set point and remote hitch control switch 23 is
actuated, AUTO PTO is disabled. According to a further feature, if
the hitch is above the AUTO PTO OFF set point and there is no hitch
movement for a predetermined time (e.g., one minute), AUTO PTO is
disabled. According to yet another feature, an operator station
seat position sensor is provided to indicate whether the operator
is in the seat of the operator station. The operator station seat
position sensor provides a seat position signal to control circuit
64. If the operator station seat position signal indicates the
operator is off the seat for more than a predetermined time (e.g.,
five seconds), AUTO PTO is disabled.
While the embodiments illustrated in the FIGURES and described
above are presently preferred, it should be understood that these
embodiments are offered by way of example only. For example, the
principles of the present invention may find applications in
construction machinery as well as agricultural machinery. In
another alternative embodiment, an additional remote throttle
switch may be provided to allow the operator to adjust the PTO
speed by, for example, remotely adjusting the engine speed or
remotely adjusting a gear coupled to the PTO shaft. The invention
is not limited to a particular embodiment, but extends to various
modifications that nevertheless fall within the scope of the
appended claims.
* * * * *
References